Rear-view mirrors that are attached to the vehicle and employed to check the area behind the vehicle include door mirrors provided at the front doors on each side of the front seats of a vehicle. As such door mirrors, electronically retractable mirrors are widely used. Electronically retractable mirrors are provided with a motor and pivot between a retracted position and a deployed position, this being the position of normal use, as the motor is driven in accordance with the operation of a switch.
The angle between the retracted position and the deployed position is different for the driver-side door mirror and the passenger-side door mirror of vehicles, with the angle on the front-passenger side being smaller than the angle than that on the driver side. Left and right electronically retractable door mirrors operate in parallel to respectively move to their retracted position or their deployed position. However, if the angle between the deployed position and the retracted position differs on the left and right, there is an offset in the timings at which the retracted positions or the deployed positions are reached.
When there is an offset in the timings at which the left and right door mirrors of a vehicle reach their retracted positions or their deployed positions, this does not always impart an appealing impression. In particular, in vehicles known as luxury cars, the ignition switch is turned OFF (for example, to ACC OFF) to move the door mirrors to their retracted positions, and the ignition switch is turned ON (for example, to ACC ON) to move the door mirrors to their deployed positions. Further, in vehicles with a keyless entry system, for example, in which locking and unlocking of the doors is performed using a wireless key (portable device) such as a smart key, control may be coordinated such that locking the doors moves the door mirrors to the retracted positions and unlocking the doors moves the door mirrors to their deployed positions. An offset in the timings at which the left and right door mirrors reach their retracted positions or their deployed positions is detrimental to the sense of luxury of such vehicles.
Japanese Utility Model Application Laid-Open (JP-U) No. S63-109238 proposes providing the drive circuit of a left-side door mirror with a speed control circuit, and lowering a voltage supplied to the motor of the left-side door mirror so as to be lower than a voltage supplied to the motor on the right-side. In JP-U No. S63-109238, the timings at which the left and right door mirrors reach their retracted positions or their deployed positions are thus matched so as to impart a sense of luxury to the vehicle.
Japanese Patent Application Laid-Open (JP-A) No. 2006-166678 proposes providing a step at which a control value for a voltage or a current is lower than during steady operation, extracting a motor rotation signal with high precision at this step, and controlling a rotation speed and drive amount of the motor based on the extracted rotation signal. JP-A No. 2006-166678 also proposes learning drive amounts for the motor. JP-A No. 2006-166678 is thus able to control, with high precision, the position of a door mirror operated by driving the motor.
Note that when the retracted position or the deployed position is reached, for example, the motor in each electronically retractable door mirror adopts a locked state, and a control device provided at the vehicle stops power to the motor when the motor has adopted a locked state. Some door mirrors are also provided with a lock detection means to detect the locked state of the motor and stops power to the motor. In a door mirror provided with a lock detection means, a control device supplies the door mirror with a voltage of a polarity that corresponds with an operation of a retraction/deployment switch, detects that the power to the motor of the door mirror has been stopped, and stops the supply of voltage to the door mirror.
However, in cases in which the left and right door mirrors are provided with lock detection means to detect the locked state of the motors and stop power to the motors, it is difficult for the control device to accurately ascertain the timings at which the door mirrors reach their retracted positions or their deployed positions. Thus, if there is an offset in the timings at which the retracted positions or the deployed positions are reached when the left and right door mirrors are retracted or deployed, this offset is difficult to eliminate, leading to a state detrimental to the sense of luxury of the vehicle.